With continuous development of Packet Transport Network (PTN) technology, the PTN network will become the major access technology for every network operator. The currently defined PTN network includes, but is not limited to the following networks: Multi-Protocol Label Switching (MPLS) network, Transport-MPLS (T-MPLS), MPLS-Transport Profile (MPLS-TP) network, Ethernet etc.
Establishment of a bidirectional LSP is of importance in PTN. And bidirectional LSPs can be classified into co-routed bidirectional LSPs and associated bidirectional LSPs. In a transmission network, because of needs in aspects such as time delay/protection/Operations, Administration and Management (OAM) detection etc. a data stream, if bidirectional, needs to pass through the same path. Because of this, RFC3473 puts forward a method for establishing a co-routed bidirectional LSP by using an upstream label.
If a PTN network is used to bear Virtual Private Network (VPN) services, then two Provide Edge (PE) endpoints are required to have a strategy controllable ability for an outer layer LSP of the same L2VPN\L3VPN, such strategy controllable ability including: consistent service levels, consistent protection etc. In addition, with the application of T-MPLS OAM and the emergence of protection among tunnels, bidirectional detection of associated switching is involved, which means that two PE endpoints need to be bound explicitly, and two unidirectional LSPs need to be associated to become a tunnel with bidirectional attributes. However, there are only unidirectional LSPs in MPLS (Multi-protocol Label Switching) packet protocols. Because of this, it is put forward in RFC5654 that the MPLS-TP must support establishment of an associated bidirectional LSP. Thus, two unidirectional LSPs can be associated controllably to maintain a unidirectional signalling docking ability, to maintain the compatibility with MPLS unidirectional LSPs of various versions and so as to operate services.
FIG. 1 is a schematic diagram illustrating LSP1/LSP2 binding of the related art. As shown in FIG. 1, LSP1 (A-D-B) and LSP2 (B-D-C-A), which are two Traffic Engineering (TE) tunnels in opposite directions, need to be associated to become a bidirectional LSP. In the related implementation scheme, binding of two reverse LSPs are designated statically at a head node and an end node. This scheme has the following shortages: (1) during the binding of the head node and the end node, a bidirectional forwarding item needs to be generated first and the existing unidirectional forwarding item is deleted subsequently, thus causing multiple interactions between a control plane and a forwarding plane, and influencing the establishment efficiency of LSPs; and (2) interference of a network management plane: two LSPs which need to be bound are designated by a network management plane with a complex process, and mismatching of two ends is possible.